1549564 - The browser stuck when loading some video streaming

Status: RESOLVED WORKSFORME

(Web Compatibility :: Site Reports, defect, P3)

Description

[Flavio]

Attachment: BrowserStuck.jpg

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:66.0) Gecko/20100101 Firefox/66.0

Steps to reproduce:

I go to the following url:
https://static3.mediasetplay.mediaset.it/player/index.html?appKey=5ad3966b1de1c4000d5cec48&programGuid=F309552501026C02&id=969089&guid=F309552501026C02

Actual results:

The browser goes in infinite loop, displaying loading animating image. Then, after some seconds, bring out the message "the browser is slowed down by a web page. how do you want to proceed?", with two choice button to stop or continue. But any choice you take the infinite loop doesn't break.
My OS details: Ubuntu-Gnome 16.04.6 LTS - Kernel: 4.15.0-48-generic #51~16.04.1-Ubuntu
Firefox v. 66.0.3

Expected results:

Start video streaming. In Chromium (chromium-browser 73.0.3683.86-0ubuntu0.16.04.1) it runs fine!

Comment 1

[Matthew Gregan [:kinetik]]

Works for me in Firefox 66.0.5 on Fedora 29 and Firefox 68 (nightly) on Windows 10.

Flavio, could you please attach a copy of your about:support page? Do you have any extensions installed? It may be worth creating a fresh profile (https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles) and retesting to see if the issue reproduces with a clean Firefox setup.

Comment 2

[Flavio]

Attachment: Firefox-About_Support.pdf

Comment 3

[Flavio]

(In reply to Matthew Gregan [:kinetik] from comment #1)

Works for me in Firefox 66.0.5 on Fedora 29 and Firefox 68 (nightly) on Windows 10.

Flavio, could you please attach a copy of your about:support page? Do you have any extensions installed? It may be worth creating a fresh profile (https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles) and retesting to see if the issue reproduces with a clean Firefox setup.

Matthew, I confirm that issue remain even if I reinstall new Firefox package, and after remove ~/.mozilla folder. Also if I restart w/o add-ons. This issue bring up ONLY with previously mentioned url (or other video streaming url of the same media production house). All that too with last FF version: 66.0.5 (see "about:support" attached output). I repeat that, instead, web browser Chromium work fine, w/o problems.

Comment 4

[Andreas Pehrson [:pehrsons]]

I was able to repro this using the firefox-trunk Ubuntu Nightly build from May 13th, as well as the regular Mozilla Nightly from May 16th.

See https://perfht.ml/2LR5VJ3

To me it looks like the site is doing something crazy. Lots (lots) of reading element.scrollHeight, and setting element.innerHTML, causing reflows. Well, there seems to be one massive reflow that's not finishing, which is probably what's blocking interaction with the page.

I took another profile at https://perfht.ml/2LOSitR that tries to capture initial load of the page. It shows a "readystatechange" event leading to the blocking code. I can't really progress further without seeing more of their code. I'm able to stop the script but the code is minified and impossible to follow. It's even harder to say whether there's a Firefox bug here or if it's the site doing something stupid, ending up in an infinite loop.

Moving to webcompat for outreach.

Comment 5

[Flavio]

I have doing some test on PC with Windows as O.S. and these works fine. It seem to depend by Linux OS. In the specific, issue bring out on Ubuntu 16.04.6 "xenial". This problem there is also on other different notebook, although this is equipped with Xubuntu, while the first with Ubuntu-Gnome, but results is the same. Nevertheless, both Linux distros works fine with "chromium-browser".

Regards.

Comment 6

[Mike Taylor [:miketaylr]]

Hi Flavio, would you mind re-testing in 68? I was not able to reproduce on my Ubuntu box.

Comment 7

[Flavio]

Hi Mike, I tested right now and it seems that work fine!!! The FF v. is 68.0.2 (for Ubuntu - Canonical - 1.0).
Thank you very much for your effort!
Best regards.
Flavio

Comment 8

[Mike Taylor [:miketaylr]]

Great, thanks!